Apple says it took new steps in 2017 to improve manufacturing workers' conditions and to create a greener supply chain, but it also reported a jump in supplier issues compared to the year before.

The tech giant has more than 3 million workers in its global supply chain to make iPhones, iPads and Apple Watch, according to the company's 12th annual Supplier Responsibility Report, which it released Wednesday.

Apple expanded the scope of its audit to include more of its suppliers -- and with it "core violations" in labor and human rights from suppliers, which range from debt-bonded labor, working-hours falsifications and underage labor. In 2017, 44 core violations were uncovered related to labor and human rights, double that from 2016.

The company said it conducted 756 assessment in 30 countries, 26 percent of which were first-time assessments.

Apple also said it clamped down on all suppliers responsible for core violations.

The Silicon Valley company ordered three suppliers that were using debt-bonded labor -- which is against Apple's policies -- to reimburse more than $1.9 million to 1,550 workers who were pressured to pay the supplier a recruitment fee to work in the factory. In one case, more than 700 contract workers were recruited from the Philippines by a private employment agency to work for a supplier through a private employment agency, and Apple oversaw the reimbursement of more than $1 million back to the workers. None of the suppliers have repeated debt-bonded labor, according to an Apple spokesperson.

Apple found 38 cases of working-hours falsifications by suppliers looking to evade its policy limiting working more than 60 hours a week. In each case, Apple alerted the supplier's CEO, put the supplier on probation and required the supplier to undergo regular labor audits.

In 2017, Apple found two cases of underage labor, involving workers ages 14 and 15 who worked in the factory using a fake ID. In both cases, the underage workers were immediately sent back home and enrolled in their choice of schools as they received wages from the violating supplier. When they reach legal working age, both workers also will be offered a job from the supplier facility.

Apple also touted its new health program, with suppliers in India and China, which teaches women about the value of nutritional, maternal and preventative health care and provides access to services, including self-examination for early cancer detection, nutrition, personal care and maternal health.

"We believe that everyone making Apple products deserves to be treated with dignity and respect and we're proud that almost 15 million people understand their workplace rights as a result of the work we've done over the years," said Apple COO Jeff Williams. "We're going further with health education programs and new opportunities for advancement at our suppliers."

Apple also launched the Factory Line Leader Program, which seeks to educate factory workers in technical and soft skills from vocational schools so they can become qualified line leaders.

On the environmental front, Apple says all of its worldwide iPhone final assembly sites have now been certified as zero waste to landfill. The company achieved a 37 percent average wastewater reuse rate and saved over 5.1 billion gallons of freshwater.